Yo mama's so rich, she's got her own ZIP code because our country is highly segregated by wealth and she doesn't like living near poor people.
The map shows the top 3 ZIP codes in each state, and the bottom graph lists the top 100 ZIP codes overall. (click to expand) (via Experian)
The "yo mama" line at the top of this article is barely a joke, because not only are many of these ultra-rich ZIP codes very homogenous (i.e. rich people and rich people only), they're also very small—even when they're in the middle of New York City proper, where 8.4 million people live in 305 square miles.
The map itself only lists the top 3 ZIP codes from each state, but the bottom chart shows the top 100 ZIP codes overall (which leads to a big overrepresentation of New York and it's tiny neighborhood ZIP codes). As you may have also heard about NYC and other big cities, a lot of poor folks live there, too. Many of New Jersey's top ZIP codes (though not #2, New Vernon) are within a 15-minute drive from Newark...which is not one of the top ZIPs. The richest of the rich spots, however, seem to actually be retirement areas for the super-wealthy, like Miami Beach.